The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (e.g., the number of interconnected devices per chip area) has generally increased while geometry size (e.g., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs.
In semiconductor manufacturing, e.g., in middle-of-line (MOL) processing or back-end-of-line (BEOL) processing, conductive materials are used to fill openings or trenches to form conductive features such as contact plugs, vias, or conductive lines. With the scaling down of feature sizes, it has become more difficult to fill small openings or trenches.